Due to the inexperience of Phil Neville and Duncan Ferguson (who I would love) it probably won't be them. I actually think that appointing from within would be the right way to go but I understand the reasons for not doing so.
If it's an 'outsider' I'd plump for Martinez. I don't think Laudrup would stick around - he wants a European job.
Laudrup is ambitious so that rules him out. Martinez will be desperate to manage in the PL so it looks like a desperate manager and a desperate owner is match made in heaven. Other than that, i think Martinez will be looking for a new job within 2 years after Everton sack him.